A UML profile can define several different elements to extend the UML for a specific domain, platform, or purpose. Besides stereotypes, a profile can define DataTypes and Enumerations, which can be used within Stereotypes to type the tagged values. A profile can also define Classes, which can be used as base classes for stereotypes. However, a profile does not typically define instances of elements, such as Objects, nor does it define composite structures, such as Components. The intent of a profile is to adapt existing metamodel elements through the use of stereotypes, tag definitions, and constraints rather than to create instances or define system architectures. This definition and use of a profile are aligned with the guidelines in the UML 2.x Superstructure Specification, which outlines what elements a profile can define within the UML framework.